Curvature Angle Research Articles

基于 DEM 的开沟刀结构参数优化与试验

This study developed a chain counter-rotating trenching and backfilling device to reduce high tillage resistance in orchard operations. A 3D mathematical model of the trenching blade was created using Cartesian coordinate transformation. Taking curvature (β), curve angle (α), bend radius (R), and cone residual angle (θ) as experimental factors, and soil cutting resistance as the evaluation index. The optimized parameters were β=95°, α=10°, R=24 mm, θ=39°. Bench tests were performed with the optimal parameters, and the results showed that the optimized ditching blade reduced the resistance by 18.7% compared to the ordinary trenching blades. Field test results showed a 9.64% reduction in furrowing torque.

Development of a biaxial fibre Bragg grating (FBG) extensometer with axis misalignment error compensation and cloud integration for advanced slope monitoring

Abstract In the paper, an FBG-based biaxial extensometer is presented to detect ground movement, which is a crucial element in slope monitoring systems. Multiple FBGs were used as displacement sensors to establish sensing nodes at various locations along an HDPE pipe. Each sensing node comprises two FBGs for biaxial displacement measurement. A numerical model based on characterization matrix equation is formulated to estimate the lateral displacement vectors using the displacement data obtained from all FBG sensors. The inclusion of torsion effects in the characteristic matrix equation addresses the misalignment error in the principal axis at each sensing node, thereby enhancing estimation accuracy. Through characterization tests, there is a notable enhancement in the accuracy of the displacement vector estimation. Finally, the proposed extensometer is being examined to determine if it can be integrated with the cloud network for remote monitoring. Various random displacement shapes and curvature angles have been tested. The results demonstrate a strong similarity between the shapes reconstructed by the model and the actual ones.

Comparison of the effect of different irrigation activation systems on the amount of apical extrusion of irrigation solution in teeth with severely curved canals.

This study aims to quantitatively compare the effects of standard needle irrigation (SNI), passive ultrasonic irrigation (PUI), EDDY, photon-initiated photoacoustic streaming (PIPS), and shock wave-enhanced emission photoacoustic streaming (SWEEPS) on the apical extrusion of irrigation solutions in teeth with severe canal curvature. Seventy-five teeth with a single root and canal, and curvature angles ranging from 20° to 40°, were selected for this study. Root canal curvatures were measured from buccolingual and mesiodistal radiographs using ImageJ software (version 1.48v; National Institutes of Health, Bethesda, MD, USA). The samples were randomly assigned to five groups (n = 15) based on the irrigation activation methods: SNI, PUI, EDDY, PIPS, and SWEEPS. An irrigation activation procedure was performed for 90s using a total of 6ml of 2.5% sodium hypochlorite (NaOCl) (Wizard, Istanbul, Turkey) in all samples. The Myers-Montgomery experimental model was used to simulate periapical tissues and limit the amount of extruded solution. The extruded irrigation solution was collected from the drainage cannula using an insulin syringe. The data on the amount of apical extrusion of irrigation solution were analyzed statistically using the Kruskal-Wallis and Mann-Whitney U tests, with a significance level set at P < 0.05. While the highest mean solution extrusion was observed in the SNI and PUI groups, the PIPS group showed less extrusion compared to the other groups. However, no statistically significant difference in the amount of apical extrusion of irrigation solution was found among all the irrigation activation methods tested. Within the limitations of this study, all irrigation activation methods tested on teeth with severe curvature resulted in a certain amount of solution extrusion. However, no significant difference was identified among the irrigation activation methods tested. When these irrigation activation methods are tested on teeth with varied canal anatomies, the amount of apical extrusion of the irrigation solution may vary.

Comparison of Edgefile X3-One Curve File Systems and Cold Lateral Condensation-Single Cone Filling Techniques in Monoblocks With Simulated Curved Root Canals

Objective: The present study aimed to compare the effects of EdgeFile X3 and One Curve files on the angle of curvature and the effectiveness of cold lateral condensation and single-cone filling techniques in monoblocks with curved root canals. Method: One hundred and eight monoblocks were divided into three main groups according to the curvature angle. Main group I had curvature angle of 5° at a distance of 6 mm from the root apex; main group II had curvature angle of 20° at the same distance from the root apex; and main group III had curvature angle of 20° at the same distance and curvature angle of 30° at a distance of 12 mm from the root apex. The main groups were divided into sub and end groups according to the use of Edgefile X3, One Curve, cold lateral condensation and single-cone techniques. Results: With the One Curve, more straightening was observed in the curvature angle of the root canals in main group III. In main group III, there was a significant negative correlation between the change in apical and coronal curvature angles and the gutta-percha ratio and a significant positive correlation with the canal sealer ratio for both techniques. Conclusions: With the Edgefile X3 file system, the shaping process took less time and the angular change was less. It was concluded that the main determinant of higher gutta-percha ratio was the filling technique used and the single-cone filling technique was more successful. Keywords: Transportation, Resin block, EdgeFile X3, One Curve, Single-cone, Cold lateral condensation

The aortic-vertebral distance is more associated with axial plane deformities than coronal and sagittal deformities in idiopathic scoliosis patients of Lenke types I and II.

Although idiopathic scoliosis is a common three-dimensional deformity, there is a lack of studies evaluating the associations between the aortic-vertebral distance (AVD) and spinal deformities in all planes. The study therefore aimed to evaluate how the coronal and sagittal curvature, vertebral rotation and aortic-vertebral angle (AVA) affect the AVD in idiopathic scoliosis. The AVD, AVA, vertebral rotation and curve angles were measured on preoperative magnetic resonance imaging and radiographs in 46 patients who underwent posterior spinal fusion with pedicle screw instrumentation for idiopathic scoliosis Lenke types 1 and 2. Associations between variables were examined using correlation and multivariable regression analyses. A significant weak to strong correlation was found between the AVD and AVA, and the AVD and vertebral rotation (r = 0.315 to 0.712) within the thoracic curve. The sagittal kyphosis and coronal Cobb angles showed weak correlations with the AVD (r = -0.311 to 0.338). The regression model for the apical vertebral level, which included the four variables, explained 40% (R²=0.40) of the variation in AVD. AVA and vertebral rotation were significantly associated with AVD (p < 0.01 for each), together accounting for 34% (R²=0.34) of the variation. The shortest distance from the aortic wall to the vertebral body wall is primarily influenced by vertebral rotation and the AVA within the thoracic curve. Thus, these factors need to be taken into consideration when planning pedicle screw placement especially in freehand techniques.

The effect of arm positions used during radiography on spinal alignment parameters assessed by 3D ultrasound imaging in adolescents with and volunteers without idiopathic scoliosis.

Clinicians monitor scoliosis progression using multiple radiographs during growth. During imaging, arms must be elevated to visualize vertebrae, possibly affecting sagittal alignment. This study aimed to determine the arm position that best represents habitual standing (and possibly allowing hand-based skeletal maturity assessment) to obtain frontal and lateral stereo-radiographs as measured using frontal, sagittal, and transverse angles. Females with and without, and males with Adolescent Idiopathic Scoliosis (AIS) were recruited consecutively. Patients were scanned using 3D Ultrasound imaging (3DUS), in 10 arm positions; habitual standing, arms supported anteriorly at 60° flexion, fingers to clavicle, chin, zygomatic, and eyebrows, arms abducted 90°, hands on wall, on blocks, and unsupported. Axial vertebral rotation (AVR) differences, frontal, and sagittal curve angles were measured. Repeated measures ANOVAs with Sidak post-hoc tests compared positions. Ninety females with and without AIS with mean age, and height of 17 ± 4years, and 162 ± 6cm, and ten males with AIS of 16 ± 3years, and 174 ± 11cm, respectively, were included. Female AIS single-curve showed larger curves in standing in all positions excluding hands on blocks (p > 0.05). Sagittal parameters showed decreases in kyphosis in arms abducted 90° and increases in lordosis in fingers to cheeks/eyebrows (p > 0.05). AVR twist was not significantly affected by position. Male AIS showed comparable results to females, but no significant differences weredetected. No position represented habitual standing for all groups. When arms are raised, decreases in curve angle were shown in single-curve patients, kyphosis decreased, and lordosis increased in all groups. Most accurate positioning for all parameters was in fingers to clavicle/chin position.

Machine learning can predict surgical indication: new clustering model from a large adult spine deformity database.

The choice of the best management for Adult Spine Deformity (ASD) is challenging. Health-related quality of life (HRQoL), comorbidities, symptoms and spine geometry, along with surgical risk and potential residual disabilityplay a role, and adefinite algorithm for patient management is lacking. Machine learning allows to analyse complex settingsmore efficiently than other available statistical tools. Aim of this study was to develop a machine-learning algorithm that, based on baseline data, would be able to predict whether an ASD patient would undergo surgery or not. Retrospective evaluation of prospectively collected data.Demographic data, HRQoL and radiographic parameters were collected. Two clustering methodswereperformed to differentiate groups of patients with similar characteristics. Threemodels were then used to identify the most relevant variables for management prediction. Data from 1319 patients were available. Three clusters were identified:older subjects with sagittal imbalance and high PI, younger patientswith greater coronal deformity and no sagittal imbalance,older patients with moderate sagittal imbalance and lower PI.The group of younger patients showed the highest error rate for the prediction (37%), which was lower for the other two groups (20-27%). For all groups, quality of life parameters such as the ODI and the SRS 22 and the Cobb angle of the major curve were the strongest predictors of surgical indication, albeit with different odds ratios in each group. Threeclusters could be identifiedalong with the variables that, in each, are most likely to drive the choice of management.

Spinal Alignment and Pain: An Assessment of Amateur Road Cyclists-A Pilot Study.

Cycling involves specific body positions that, when maintained for prolonged periods, may affect spinal curvature and increase the risk of pain-related issues. This study aimed to evaluate sagittal spinal curvatures, the prevalence of pain in spinal segments, and their interrelation among amateur road cyclists. Methoods: The research included 30 male participants aged 18-48 years. Pain severity was assessed using the Visual Analog Scale (VAS) and Laitinen scale, while spinal curvature was evaluated with an electronic inclinometer. Results showed no statistically significant differences in spinal curvature angles between cyclists with and without pain complaints (p = 0.056). However, tendencies were noted, such as higher mean VAS scores for lower back pain (4.90) compared to neck pain (3.38), and variations in parameters like Beta, LL, and KGP. While the findings did not confirm clear distinctions, they suggest trends indicating potential links between spinal curvatures and pain occurrence. These results underscore the importance of further studies involving larger cohorts to verify these observations and explore the biomechanical adaptations associated with amateur cycling. Insights from such research could inform strategies for preventing and managing spinal pain among cyclists.

Effect of curvature angle and structural configurations on dynamic performance of honeycomb sandwich structures

The aim of this study is to investigate the effects of curve angle and structural parameters on ballistic performance of honeycomb sandwich structures. In the study, high-velocity impact simulations were performed in LS DYNA finite element program to investigate the effects of honeycomb structural parameters, curve angle, residual velocity, specific energy absorption (SEA) and damage mechanism. Progressive damage analysis based on the combination of cohesive zone model (CZM) and bilinear traction-separation law was performed. The ballistic limit value increased by 41.9% when the facesheet thickness increased by two times. When the cell wall thickness increased by five times, the ballistic limit value increased by 13.3%. When the core height was two times increased, the ballistic limit velocity value increased by 2.076 times. Although the ballistic limit velocity value of the CFRP Facesheet and Aluminum (Al) core sandwich structure is 7.14% lower than the all Al specimen, the SEA value is 9.47% higher. When the curve angle increases from 0˚ to 180˚, the ballistic limit value decreases by 22.8%. In general, this study provides useful information about the design of ballistic structures, parameters affecting their performance and their effects.

Introduction of curvature index and improvement of calibration curves used in ion chromatography (IC), atomic absorption spectrometry (AAS), UV-Vis spectrophotometry and catalytic combustion

The calibration curve represents the relationship between known CRM and the response of the instrument (e.g absorbance). Most of the time, in analytical chemistry standards, the linear function (of the 1st degree) is used to characterize the calibration curves. This, at first glance, has some major advantages: simple equation, simple linearity estimation criterion, and easy way of calculation. However, from a quality point of view, the grade 1 calibration curve does not characterize a working domain very well, because it does not take into account the curvature and has larger residuals. Here we show that, most of the time, the non-linear secondary function fits the calibration curves much better (argument valid for UV-Vis spectrophotometry, atomic absorption spectrometry (FAAS and ETAAS), catalytic combustion and ion chromatography (IC)), having lower residuals, but also a higher coefficient of determination, R2. The limitation of the secondary non-linear function use is given by the insufficiency of data related to its qualitative characterization. Through this work, we have introduced new characterization criteria for non-linear secondary functions such as curvature angle and curvature index. Although in the specialized literature, the term linearity of the calibration curve has existed for a long time, in reality it has not been fully interpreted. The curvature index developed in this work allows the controlled implementation of non-linear curves, but also with increasing the precision of the results. The curvature index characterizes the degree of curvature of the 1st or 2nd degree calibration functions. Using the 2nd degree calibration function allows the improvement of the obtained results, and curvature parameters (curvature angle and curvature index) allow qualitative characterization of many data sets used for calibration. The degree of curvature of a calibration curve is a new term not found in the literature, which will allow their characterization from a qualitative point of view.

Reliability of a Measurement Method for Upper Limb Raised Standing Spinal Alignment Using a Smartphone Inclinometer Application.

To evaluate the reliability and validity of spinal alignment measurements in the raised arm standing posture using a smartphone app. An inclinometer is a reliable tool for measuring spinal alignment. Measurement of static standing posturespinal curvature angles using smartphone inclinometer applications has been investigated in the lumbar spine but has not been reported for the thoracic spine. However, the sacral vertebrae were used as the reference point for the measurement of the lumbar spine, and the method of palpation of the sacral vertebrae was unclear. No measurement methods, including inclinometers, have been found for upper limb elevation. Thoracic kyphosis and lumbar lordosis angles were measured in 18 healthy young adults (mean age: 21.0 ± 3.5). Measurements were taken in the raised standing posture. The points of measurement included angle α at the thoracic spine (T)1/2, angle β at the T12/lumbar spine (L)1, and angle γ at the L4/L5 spinous processes. The thoracic kyphosis angle was calculated as the sum of α and β, while the lumbar lordosis angle was the sum of β and γ. Two raters measured these angles twice using the same smartphones. Inter-rater reliability was assessed using intraclass correlation coefficients (ICC 2.1), and measurement precision was determined by calculating MDC95 from the ICC values.Validity was also carried out on 12 healthy young adults (age: 20.8 ± 4.0 years). The measurement points were the same as described above, and two types of measurements were taken with a smartphone and an inclinometer; the results of the two types of measurements were used to determine the relationship using Pearson's correlation coefficient. During upper limb raising, the smartphone's ICC (95% confidence interval) was 0.92 (0.81-0.97) for thoracic kyphosis and 0.90 (0.74-0.96) for lumbar lordosis. The MDC95 values indicated acceptable precision, with 7.00° for thoracic kyphosis and 9.95° for lumbar lordosis.All correlation coefficients between inclinometers and smartphones were above 0.9 for both the thoracic and lumbar spines. Measuring spinal alignment angles using a smartphone inclinometer app in the raised standing posture demonstrates good reliability for inter-rater comparisons.It was also good with regard to validity.

CBCT evaluation of the shaping characteristics of five different file systems in mesial canals of mandibular first molars – An ex vivo study

Cone-Beam Computed Tomography (CBCT) has revolutionized endodontic research by providing detailed 3D imaging, crucial for assessing the shaping characteristics of endodontic file systems. In the challenging mesial canals of mandibular first molars, where complex anatomy often complicates treatment, CBCT offers precise evaluation of how different file systems shape these canals. This ex vivo study compares five distinct file systems, analysing their ability to maintain the original canal curvature and ensure effective cleaning. The study aims to identify the most effective file systems, potentially improving clinical outcomes in endodontic therapy. This ex vivo study compared the shaping characterstics of five Ni-Ti rotary File Systems, File Univesal X7 Edge Endo, Bassilogic ProDesign Logic, Gen Endo Coltene Whaledent Pvt. Ltd., Endo Star E3 Azure Basic, Mani Jizai using Cone Beam Computed Tomography (CBCT). One hundred extracted human permanent mandibular first molars with mesial root curvature angles ranging from 20-30 degrees were divided into five groups (n=20 each). The teeth were imaged using CBCT with CS9300 equipment, set at 84 kV, 5 mA, and a 10.8-second exposure, achieving a resolution of 90 microns and a slice thickness of 76 microns to obtain a pretreatment outline of the root canals. All scans were reoriented along the x, y, and z axes. Canal transportation and root canal volume were evaluated at 0.0, 1.0, 2.0, 3.0, 4.0, and 5.0 mm intervals. The mean differences in volume and area were analyzed using one-way ANOVA to determine the variance between the five different file groups. Gen Endo File System did the least modifications in the Canal Area and Volume. Within the parameters of this study it was concluded that GEN ENDO Files did the least modifications in canal anatomy as compared to other groups.

Which Method of the Radiologic Measurements of the Angle of Curvature in Idiopathic Scoliosis is the Most Reliable for an Inexperienced Researcher?

The aim of the examination was to determine which of the three measurement methods Cobb (CB), Ferguson (FR), and Centroid (CN) has the best repeatability and reliability when the measurements are made by inexperienced researchers. Three researchers (from the student research group) measured the angle of spine curvature on X-rays of the entire spine in standing anteroposterior view in 50 patients with severe idiopathic scoliosis qualified for surgery. Cobb, Ferguson, and Centroid methods were used. One of the researchers repeated all examinations twice at 3-week intervals. The measurements were compared with each other using the intraclass correlation coefficient (ICC) method. Values less than 0.5 are indicative of poor reliability, values between 0.5 and 0.75 indicate moderate reliability, values between 0.75 and 0.9 indicate good reliability and values greater than 0.90 indicate excellent reliability. The ICC (inter-rater) between the researchers' measurements was 0.9387 for CB, 0.9169 for FR, and 0.9061 for CR. Whereas the ICC (intra-rater) between measurements taken by a single researcher was 0.9824 for CB, 0.9088 for FR, and 0.9546 for CR. The above results show that Cobb angle measurement method is the most reliable for measuring the curvature angle of the spine for novice researchers. Although it seems to be difficult to measure, it provides the most repeatable results.

Systemic Effects of Molar and Incisor Biting on Walking Direction With and Without Visual Feedback

Gait stability and walking direction control are conventionally attributed to coordination among somatosensory, visual, and vestibular systems. Recent evidence of functional interdependence between masticatory and neuromuscular systems indicates that the stomatognathic system is neurologically integrated with various body systems relevant to movement planning and execution. This study investigated the effects of unilateral molar biting and incisor biting on walking with and without visual feedback. A cohort of 31 healthy young adults aged 21 to 30 years (average age of 23.93 ± 1.89) participated in this study. Three types of errors in walking direction (angle error, position error, and curve error) were computed. Our findings indicate that, in right-handed individuals, irrespective of visual feedback, unilateral biting caused systematic deviations toward the biting side from initiation to termination of walking. The consistent deviation in walking, particularly during unilateral right biting conditions in right-handed individuals, may indicate a complex interplay between masticatory function and gait control mechanism, potentially influenced by handedness and motor lateralization within the cortex. This study establishes a foundation for future research exploring the interrelation between bite location, visual feedback, and motor control in diverse populations. This research may provide insight for more efficient interventions for gait-related disorders.

Does a delay of surgery due to a multidisciplinary screening process result in neuromuscular scoliosis curve progression in complex Cerebral Palsy?

While surgical intervention of scoliosis in cerebral palsy (CP) patients has shown notable improvements in quality of life, the high risk of post-operative complications in CP patients necessitates careful preoperative optimization. A preoperative multidisciplinary (Multi-D) pathway at our tertiary pediatric hospital in effect since 2014 led to a significant reduction in mortality at one year. However, such a strategy delays surgery, potentially increasing the risk of curve progression. This study aims to elucidate the impact of the Multi-D screening process on curve progression in neuromuscular scoliosis among complex CP patients. A retrospective review of all CP patients with scoliosis at a tertiary care center from 2012 to 2020 was conducted. This assessment focused on the progression of the major Cobb angle from the time of the indications conference to surgery of patients who went through Multi-D screening. Patient demographics and perioperative variables were obtained from the electronic medical record (EPIC, Systems Verona, WI). After exclusion criteria were met, there were 85 patients who went through Multi-D, 78 of whom had surgery, and seven who did not. Surgery was delayed an average of 202 days for Multi-D optimization. We found a trend in increasing Cobb angle over time, but this correlation did not reach statistical significance (p = 0.079). 45 Multi-D surgery participants had a decrease or no change in Cobb angle and had surgery an average of 5.6 months after indications. 33 Multi-D surgery participants had an increase in Cobb angle and had surgery an average of 8.5 months after indications. Cobb angle progressed an average of 13.4° in the increased group, and - 0.4° in the decrease or no change group. There were no associations with change in Cobb angle and GMFCS, starting major curve angle, number of referrals, or intrathecal baclofen pump use according to this analysis. Multi-D optimization resulted in an average delay in surgery of 6.7 months. Patients that did not have a change in Cobb angle had surgery within 5.6 months vs. patients that had an increase in Cobb angle had surgery on average 8.5 months after indicated for surgery, with an average increase of Cobb angle of 13.4°. Level III, retrospective comparative study.

Three degrees of freedom rigid-soft coupling biomimetic hip joint driven by dielectric elastomer

Abstract Dielectric elastomer (DE) has an attractive combination of high energy density, large strain, and fast response. A growing number of DE actuators are being used as driving materials in rigid-soft coupling joints. For better structural design, the mapping relations from the musculoskeletal system of the human hip joint to the biomimetic hip joint mechanism have been established. Inspired by the human musculoskeletal system, the configuration of the three-degree-of-freedom rigid-soft coupling hip joint based on DE is proposed. The configuration includes six soft-driving limbs and one passive rigid limb. The soft-driving limb driven by the fiber-constrained dielectric elastomer actuator (FCDEA) does not contain passive rigid joints. Based on the Gent material model, the electromechanical coupling model of FCDEA is established. A mapping model is established between the voltage applied to the soft-driving limb of the biomimetic hip joint and the posture of the moving platform in the case of deflection and torsion. A single FCDEA is prepared and its electro-responsive deformation performance is tested through experiments. As a demonstration, a prototype of the biomimetic hip joint is developed. After applying voltage, the deflection angle and the torsion angle of the biomimetic hip joint are tested and the curve of voltage and rotation angle is drawn. The experimental results agree well with the theoretical predictions. This article can provide theoretical references for improving the performance of rigid-soft coupling hip joints.

Cyclic and torsional fatigue resistance of two replicalike and original brand reciprocating system

The aim of this study was to evaluate the cyclic and torsional fatigue resistance of two replicalike in comparison of the original brand reciprocating system. Material and methods: A total of 60 reciprocating instruments were used to perform the cyclic and torsional fatigue test of following systems: Reciproc Blue 25.08 (RB 25.08), Only One File Blue (OFB 25.08) and RC Blue 25.08 (RCB 25.08) (n=20). The cyclic fatigue test was performed using an artificial stainless steel canal with 60º angle of curvature and a 5-mm radius of curvature. The instruments were activated until failure occurred. The time to failure (TF) and number of Cycles to failure (NCF) were evaluated. The torsional test was performed following the ISO 3630-1. Three millimeters of the instrument tip was fastened to a small load cell and the maximum torsional strength and angular deflection were recorded using the torsion testing machine software. The fractured surface of each instrument was assessed by scanning electron microscopy (SEM). The data were analyzed using one-way analysis of variance ANOVA and Tukey’s test for Multiple comparisons at a significance level of 5%. Results: The cyclic fatigue tests demonstrated that OFB 25.08 had the highest TF and NCF than among the groups (P&lt;0.05). RCB 25.08 exhibited lowest TF and NCF (P&gt;0.05). Regarding the torsional test, the RCB 25.08 and OFB 25.08 had the highest torque than the other groups (P&lt;0.05). Additionally, RB 25.08 and OFB 25.08 exhibited highest angular deflection values than the other groups (P&gt;&lt;0.05). Conclusion: The OFB 25.08 demonstrated highest TF and NCF than the instruments tested. The RCB 25.08 exhibited lowest cyclic fatigue resistance and angular deflection.&gt; P&lt;0.05). RCB 25.08 exhibited lowest TF and NCF (P&gt;0.05). Regarding the torsional test, the RCB 25.08 and OFB 25.08 had the highest torque than the other groups (P&lt;0.05). Additionally, RB 25.08 and OFB 25.08 exhibited highest angular deflection values than the other groups (P&gt;&lt;0.05). Conclusion: The OFB 25.08 demonstrated highest TF and NCF than the instruments tested. The RCB 25.08 exhibited lowest cyclic fatigue resistance and angular deflection.&gt; P&lt;0.05). Conclusion: The OFB 25.08 demonstrated highest TF and NCF than the instruments tested. The RCB 25.08 exhibited lowest cyclic fatigue resistance and angular deflection.

Association between final local kyphosis angle and residual back pain in traumatic vertebral fractures at the thoracolumbar junction with posterior stabilization using percutaneous pedicle screws.

There is no consensus on the association between final local kyphosis and residual back pain (RBP) after traumatic vertebral fracture. The aim of this study was to investigate whether there is an association between the final local kyphosis angle and RBP in patients with traumatic vertebral fractures at the thoracolumbar junction who underwent single posterior surgery with percutaneous pedicle screws and implant removal after fracture healing. A second goal was to determine the optimal cut-off value for the final local kyphosis angle with and without RBP. Twenty-five patients were included in the study. Age, gender, Injury severity score, level of fracture, AO classification, the McCormack Load sharing classification, and range of stabilization were collected. In addition, imaging assessment was performed to evaluate vertebral kyphosis angle, local kyphosis angle (Cobb angle), and the percentage of anterior, middle and posterior vertebral body compression at the time of injury and at the final follow-up after implant removal. The patients were divided into two groups, with and without RBP [Group RBP (+) and Group RBP (-), respectively]. Each variable was compared between groups. Cut-off values were calculated using the Youden index with receiver operating characteristic (ROC) curves. There were 12 patients in the RBP (+) group and 13 in the RBP (-) group. The two groups were significantly different only for the final local kyphosis angle, with no significant differences for the other variables. The ROC curve of the final local kyphosis angle for RBP had an area under the curve (AUC) of 0.88 (P<0.01). The optimal cut-off value for the final local kyphosis angle for RBP calculated from the Youden index was 15.85°. There is an association between the final local kyphosis angle and RBP. The optimal cut-off value of the final local kyphosis angle for RBP was approximately 16°.

Experimental and Numerical Study on Ballistic Characteristics of Vertical Water Entry for High-speed Truncated Head-type Projectiles

Abstract To achieve the ballistic control method of rapid levelling the projectile after the water entry, an asymmetric head-type design is proposed. To analyze the trajectory of center of gravity of the projectile with an oblique truncated head, comparative experiments of the vertical water entry of the projectile at different velocities was conducted using a high-speed camera to obtain the trajectory and the variation of the deflection. The effects of different cutting angles and water-entry velocities on the trajectory characteristics of the projectile and the cavity flow field were investigated by numerical simulations. The results indicated that the increasing cutting angle of the projectile will increase the curvature and deflection angle of the trajectory after the projectile enters water, and the yawing angle of the projectile will increase by 5 degrees for every 5 degrees increase of the cutting angle in the study area within 9 milliseconds. The asymmetric head-type of the projectile will affect the shape of the cavity, and the cavity will appear an asymmetry and form cavities at the head and tail, respectively, and the flow field pressure will change drastically.

Investigation of The Effect of Radius of Curvature on Buckling Load in Thin-Walled Beams

This study examines the effect of curvature radius on the buckling behavior of thin-walled beams, which are commonly used in aerospace, automotive, and structural engineering due to their high strength-to-weight ratios. The buckling phenomenon, which represents a critical failure mode for thin-walled hat-shaped structures, was investigated under axial loading through the utilization of numerical methods. A nonlinear analysis was conducted using ANSYS Workbench to model three distinct geometries with varying curvature angles and identical dimensions. The models were subjected to analysis in order to ascertain the critical buckling loads and reaction forces at a displacement of 1 mm, with a particular focus on both nonlinear and post-buckling behavior. Given its importance in structural applications, Aluminum Alloy NL was selected as the material. The eigenvalue buckling analysis identified the critical loads for the first ten modes, revealing that models with higher curvature angles demonstrated more stable buckling characteristics, whereas those with smaller angles were more prone to local deformation. A post-buckling analysis was conducted to ascertain the nonlinear load-bearing capacities of these structures.